This invention regards a method of removing gases from water. More particularly, it regards a method which is particularly suited for removing enough of the free oxygen in water e.g. to neutralize organisms in a ship's ballast water or to allow the water to be injected into a petroleum well. The invention also covers a device for implementing the method.
For technical reasons, a ship must carry a certain amount of cargo when sailing. As is well known, cargo that does not produce income is called ballast.
As it is relatively easy to load and unload, seawater is to a large extent used as ballast. Many species of organisms are transported with the ballast water from the loading site to the unloading site.
A great proportion of the living organisms die in transport, and more die when released at the unloading site. However, favourable conditions may allow a stock to survive and reproduce.
The introduction of alien organisms in a new place is known to have had disastrous consequences for among other things the fisheries of entire ocean areas.
International bodies are currently working out new guidelines on the treatment of ballast water with an eye to neutralizing organisms. The guidelines emphasize that the treatment of ballast water must be safe, environmentally acceptable and inexpensive in use, and it must work.
It has been proposed that ships change ballast while underway, in order to reduce the risk of carrying species to a new area. The method has met with resistance, especially from the authorities in those countries located near possible change-out areas.
When producing petroleum, it may be expedient to pump water is into a reservoir. The purpose of this may be to make residual petroleum gather on top of the water in order to achieve enhanced recovery.
A large proportion of the free oxygen in the water must be removed prior to pumping this into the reservoir.